The proposed research addresses three problems associated with performing incremental evaluation of attribute grammars: (1) multiple asynchronous subtree replacements in the parse tree that are initiated by external agents, (2) segmentation of the parse tree according to granularity of access rights with respect to these agents, and (3) distribution of the segments across a reliable network. The research focuses on one exemplary application, distributed multi-user language-based environments, where the parse tree represents a program being developed, the subtree replacements are changes to the program, the external agents are programmers, the granularity of segments corresponds to the modularization of the program, and the nodes of the network are the programmers' workstations.